DE2321196A1 - REMOVAL OF MERCURY FROM SEWATER - Google Patents

Description

DR. MÜLLER-BQRE DIPL-IH ^ f .. DR. MANITZ DIPL-CHEM. DR. DEUFEL

DlPL-ING. FINSTERWALD dipl.-ing. GRÄMKQW

PATENT LAWYERS 9 ^ 91 IQR

D / Sh - S 2531

Sumitomo Chemical Company, Limited Osaka, Japan

Removal of mercury from wastewater

Priority: Japan from April 26, 19? 2, ftr. 43O3V72

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Dr. Müller-Bor «Or. Manitz ■ Dr. Deufel - Dipl.-Ing. Finsterwald Dipl.-Ing. Grämkow Braunschweig, Am BOrgerpark 8 β Munich 22, Ffobert-Koch-Strasse 1 7 Stuttgart-Bad Cannstatt, Marktstrasse Telephone (0531) 73887 Telephone (0611) 293645, Telex 5-22050 mbpat Telephone (0711) 567261 Bank: Central Cash Register Bayer. Volksbanken, Munich, account number 9622 Post check: Munich 95495

The present invention relates to a method for removing and recovering mercury from wastewater, the in the production of a-anthraquinone sulfonic acids using of mercury or compounds thereof as a sulfonation catalyst accrues. The invention also relates to the method for the virtually complete removal of mercury from a-anthraquinone sulfonic acids, which are formed as a product

be det.

The α-anthraquinone sulfonic acids described herein include mainly anthraquinone-1-sulfonic acid, -1,5 * -äisulfonic acid, -1,8-disulfanoic acid and the alkali salts and ammonium salts of that.

To α-anthraquinone sulfonic acids in high yield by SuTonation To form anthraquinone, it is absolutely necessary to use mercury or mercury-containing compounds as a catalyst to use. The wastewater produced during the manufacturing process therefore usually contains a considerable amount of mercury, which should be removed from it, namely the mercury content of the waste water up to about 35 to 600 mg / 1 as in Japanese Patent Publication, for example No. 22335/1971.

Among the previously known methods for removing mercury from the wastewater in the production of a ^ anthraquinone sulfone— acids include a method where the wastewater is treated with carbide slag or with lime, and where in the calcium-containing precipitate thus formed mercury brought to coprecipitation or absorption and removed from the solution system; further a method where mercury is used Adsorption on activated carbon or on a metal powder such as iron powder, is brought; a method used in Japanese

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Patent publication Mr. 22335/1971, wherein wastewater is treated with a halogenate in the presence of hydrogen halide and then with hydrogen sulfide or a salt thereof; and a method as described in Chem. Abstracts 62 , 11523-g (1965), wherein the waste water is treated with potassium chlorate and then with sodium sulfide. With these methods, however, the so-called adsorption process is not industrially satisfactory because it has only a low degree of efficiency, and the last two methods also have the following disadvantages: The mercury content of the final waste water from this process still remains around 0.01 ppm, and this value is unsatisfactory from the point of view of environmental pollution and, moreover, the mercury contained in the α-anthraquinone sulfonic acids formed as a product should be removed separately, which is extremely difficult, as in, for example, U.S. Patents 2,999,869 and 2,900 397 is described. Second, the method of treatment with sodium sulfide should be carried out at a pH of about 6, so that after the treatment with halogenate it is necessary to neutralize the acidic solution, which contains sulfuric acid, for example at a concentration of about 20 percent by weight in the case of the Process from the production of potassium anthraquinone 1,8-disulfonate, so that a large amount of alkali is required, which means an economic and technical disadvantage. On the other hand, the use of the cheap carbide slag as alkali for the neutralization leads to a large volume of precipitate, which contains part of the mercury, which necessitates troublesome post-treatment of the precipitate.

The aim of the invention is to remove mercury from the Wastewater produced during the process for the production of oc-anthraquinonesulphonic acids in the presence of mercury or mercury-containing compounds, as well as the simultaneous practically complete

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dige removal of mercury from the product formed oc-anthraquinone sulfonic acids.

The removal of mercury from anthraquinone-oc-sulfonic acids has been studied and doing a remarkably effective process for the recovery of mercury from both anthraquinone sulfonic acids as well as found from the wastewater, which consists in the acidic solution of an a-anthraquinone sulfonic acid with a Treat thiosulfate to precipitate most of the mercury as mercury sulfide, which is then separated and recovered. It was also found that it is possible to use the Virtually completely remove residual mercury or mercury compounds from wastewater by using this thiosulphate treatment combined with another treatment, whereby. that obtained when the anthraquinone-a-sulfonic acids are salted out Wastewater with a halogenate in the presence of hydrogen halide and then with a mercury-adsorbing substance or with Thiosulfates is treated.

Accordingly, the invention relates to a method for removing and recovering mercury or mercury-containing compounds from a solution of α-anthraquinonesulfon acids or their salts, the mercury or a mercury-containing compound contains that have been used as a sulfonation catalyst, which consists in (a) precipitating the solution with thiosulfate treat the mercury or the compound containing mercury as mercury sulfide, and the precipitate to filter off and (b) to separate the α-anthraquinonesulphonic acids or their salts by salting out, the waste water with a halogenate to treat in the presence of a hydrogen halide, and to treat the waste water obtained with a mercury adsorbent in order to remove the mercury contained therein or the mercury-containing To adsorb the compound, or to treat it with a thiosulphate to remove the mercury or precipitate the mercury-containing compound as mercury sulfide.

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According to the invention it is possible to measure the mercury content of the final effluent to below 0.003 ppm.

Specific embodiments of the invention are as follows:

An acidic solution containing α-anthraquinone sulfonic acids, such as they are obtained by the conventional method, is reacted with thiosulfates to make mercury as mercury sulfide precipitate, which is filtered off. The filtrate is then salted out, around the a-anthraquinone sulfonic acid in the form of an Al- potassium salt or ammonium salt. To sewage After the salt has been filtered, hydrogen halide and a halogenate, namely a chlorate, bromate or iodate, are added, and the mixture is heated to convert the anthraquinone sulfonic acid still dissolved therein into insoluble Haiοgenoanthraquinones to transfer, which are filtered off. The filtrate is then treated with a mercury adsorbing substance in order to To adsorb mercury on it. Alternatively, the filtrate can be treated with thiosulphates to precipitate mercury sulphide, which is then filtered off.

According to the invention, the first stage comprises the conversion of most of the mercury, which acts as a sulfonation catalyst is used, in mercury sulfide, which is precipitated and then filtered off. The mercury content will be accordingly both the α-anthraquinonesulphonic acids formed and the filtrate after the acids have been filtered off are extraordinary low, which is a big plus. In the second stage, it is particularly expedient to proceed as follows: The acidic Solution after the halogenate treatment is treated with a specific mercury-adsorbing substance, for example MEP-100 (from Nippon Soda Co., Ltd. under this name available) or with thiosulfates as it is not necessary to neutralize the acidic solution with alkalis at the time

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when the filtrate has to be neutralized. The neutralization. is only carried out on the final filtrate in which the mercury content is extremely small, and accordingly only extremely little mercury flowed into the precipitates, which in the neutralization incurred even if cheap carbide slag is used as the neutralizing agent, resulting in an easy and convenient aftertreatment of the precipitates.

In the case of using other mercury-adsorbing substances must the acidic solution after the halogenate treatment with caustic soda or ammonia have to be neutralized beforehand to a pH effective for each substance. In each case the Mercury content of the final wastewater reduced to below 0.005 ppm,

To the. Thiosulfates used in the invention include sodium thiosulfate, Ammonium thiosulfate, potassium thiosulfate and calcium thiosulfate. The amount of thiosulfate used in this first stage is the simple to multiple weight amount, preferably 3 to 50 times the amount by weight and in the second stage 100 times or more, preferably 500 to 5000 times Amount by weight of the stoichiometric amount calculated using the following equation:

Hg ^{+ 2} + Na ₂ S ₂ O ₃ + H ₂ O «HgS + H ₂ SO ₄ + 2Na ⁺

The temperature for the thiosulfate treatment in both the first and second stages is any temperature at which α-anthraquinone sulfonic acid is dissolved. It is preferably from 80 ⁰ C to the reflux temperature. The time required for the thiosulfate treatment depends on the temperature at which the treatment is carried out, but is usually 3 to 10 hours.

The higher the treatment temperature, the shorter it is of course the treatment time. So is 5 hours or more for one

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Temperature above 90 ^° C. or 5 hours or more at a temperature above 80 ^° C. is preferred.

The hydrogen halides used in the invention are hydrogen chloride, hydrogen bromide or the like, and the amounts to be used are 0.1% by weight or more, preferably 1 to 5 percent by weight, based on the to be treated Solution.

Examples of halogenates, i.e. chlorates, bromates and iodates, are the sodium and potassium salts, e.g. sodium chlorate, Potassium chlorate, sodium bromate, potassium bromate and the like, and the amount to be used is 1 mole or more, preferably

1 to 3 moles per mole of anthraquinonesulphonic acid contained in the to be treated Solution remains.

The treatment temperature with the Halogenates is above 50 ⁰ C and is preferably between 80 ⁰ C and the reflux temperature, and the treatment time is 2 hours or more, preferably

2 to 6 hours. The treatment with the halogenates converts the remaining anthraquinone sulfonic acid into unlp search shark ο geno anthraquinone and on the other hand converts mercury in the solution from a complex form to an ionic form, which is the subsequent Removal treatment facilitated.

Among the mercury adsorbents used in the invention Substances include dithizone type chelate resins, iminodiacetic acid type ohelate resins, thio compounds, and dialkyldithiocarbamic acid compounds and urea-formaldehyde type sulfur-containing chelating resins.

For examples of mercury adsorbing substances used in the invention and commercially available,

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include, for example, ¹ MEP-100 "(available from Nippon Soda Co., Ltd.)," Santhio .HI "(available from Sankyo Kasei Co., Ltd.), chelate resin for mercury adsorption (under this name from Hokuetsu Tanso Co., Ltd.) The treatment method using these mercury adsorbing substances includes the column method as well as the batch batch method, and MEP-100 and the "chelate resin for mercury adsorption" can be used with advantage in the column method, the pumping speed preferably being 2-5 On the other hand, "Santhio N-1" or dialkyldithiocarbamic acid compounds can be used with advantage in the batch process, the treatment time being 30 minutes or more, preferably 30 to 180 minutes.

With regard to the pH of the solution to be treated, the appropriate pH range varies with the type of mercury adsorbent Means. It is, for example, 1.5 to 6 for "Santhiol N-1", 5 to 8 for chelating resins of the dithizone type and the "chelating resin" for mercury adsorption ", 2 to 4 for chelating resins of the iminodiacetic acid type and 7 *> is 9 for dialkyldithiocarbamic acid compounds. Therefore, before using the mercury-adsorbing substances, a large part of the substance to be treated should be Solution containing sulfuric acid can be neutralized with a large amount of alkali. In the case of "MEP-100", however, the The solution to be treated should be made in the normal, strongly acidic state. Neutralization with alkalis is unnecessary.

As mentioned above, the method of the invention has the advantage that it has remarkable percent removal of mercury can be increased and used with advantage as an industrial process as compared with conventional processes. The procedure the invention provides an extremely effective method of preventing environmental pollution.

309845/1104

The following examples illustrate the invention. Parts and Proent data are based on weight.

example 1

100 parts of sodium thiosulfate (Ha ₂ S ₂ O, ₂ given, the mixture is reacted under reflux for 3 hours.

The solution is then ^{cooled to 30 °} C. in order to precipitate mercury sulfide, which is then filtered off. The Piltrat is heated to 85 ⁰ C and 820 parts of a concentrated solution of potassium chloride are added to precipitate Kalrumanthrachinon-1-sulfonate, which is then filtered and washed with 1000 parts of a 5% solution Ealiumchloridlo is washed. The 11,000 parts of the wastewater obtained in this way have a mercury content of 3 ppm and 1 % anthraquinone sulfonic acid remains dissolved in it.

The mercury content of Ealium Anthraquinone-1-sulfonate as a dry product is 1/35 compared to the mercury content if the thiosulfate treatment is omitted.

220 parts of 35% strength hydrochloric acid and 41 parts of sodium chlorate are then added to the 11,000 parts of waste water, and the mixture is ^{reacted at 80 to 85 °} C. for 4 hours.

The solution is cooled to 30 ⁰ C to precipitate precipitate, which are then abfiltiiert. The filtrate is passed through a column (18.5 mm internal diameter) packed with a 50 ml bed of the "MEP-100" so that about 200 times the bed volume of piltrate is carried out, the flow rate being 2 bed volumes per Hour. The mercury content

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..- ■ ίο -

of the filtrate that is passed through the column is below 0.002 ppm.

The use of 57 parts of potassium bromate instead of sodium chlorate "Using the above procedure gives the same result.

Example 2

In the procedure according to Example 1, the filtrate is heated from the treatment with hydrochloric acid and sodium chlorate to 100 ⁰ C, and 20 parts of sodium thiosulfate (NapSpO ,, · 5HpO) are added, and the mixture is stirred for 3 hours at the same temperature, then at Cooled to 30 ° in order to precipitate precipitates, which mainly consist of mercury sulphide, which are then filtered off. The mercury content of the final filtrate is 0.003 ppm.For comparison purposes with the above-mentioned procedure using sodium chlorate and sodium thiosulfate, the filtrate is adjusted to pH 6 with caustic soda, and 63 parts of a 10% solution of sodium sulfide are added at 25 ^° C. and the mixture is stirred at this pH for 2 hours to precipitate precipitates, which are then filtered off. The mercury content of the final filtrate is 0.02 ppm.

Example 3

1000 parts of a wet filter cake of anthraquinone-1,5-disulfonic acid (containing 446 parts of anthraquinone-1,5-disulfonic acid and 520 ppm of mercury), as obtained in the usual manner, are dissolved in 4000 parts of water and 20 parts Sodium thiosulfate (NaoSoO ^^ H ^ O) are added and the mixture is heated and reacted under reflux for 3 hours. Thereafter, the solution is cooled to 30 ⁰ G to precipitate mercury sulfide which is then filtered off. The filtrate vxd heated to 90 ⁰ C and by adding 750 parts of sodium

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Salted out chloride, which leads to the deposition of sodium anthraquinones, 5-disulfonate, which is then filtered off and washed with cold water. 6000 parts of the filtrate obtained in this way have a mercury content of 2 ppm and a sulfuric acid concentration of 1.8%. The anthraquinone disulfonic acid concentration is 0.6%. 120 parts of 35% hydrochloric acid and 14 parts of sodium chlorate are then added to 6000 parts of this filtrate, and the mixture is then reacted ^{at 95 to 100 ° C. for 3 hours.} The filtrate is then cooled to 30 ° C. in order to precipitate precipitates, which are then filtered. The filtrate is neutralized to pH 7 with 330 parts of 40% strength sodium hydroxide solution and passed through a column (with an internal diameter of 18.5 mm) which is packed with "chelate resin for mercury adsorption ^> with a bed volume of 50 ml. Es 1000 bed volumes of the filtrate are passed through at a flow rate of 2 bed volumes per hour.The mercury content of the filtrate passed through the column is less than 0.003 ppm.

Example 4

The filtrate obtained in Example 3 after filtering off the precipitate of the Natriumchloratbehandlung is neutralized with 320 parts of 40% sodium hydroxide solution to pH 4, and then 60 parts of "Santhiol N-1" are added, and the mixture is stirred for 1 hour at 30 ⁰ C. The mercury content of the filtrate after filtration is 0.003 ppm.

Example 5

After filtering off the precipitate of the sodium chlorate treatment The filtrate obtained according to Example 3 is 310 parts 40% sodium hydroxide solution neutralized to pH 3 and passed through a column

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of 18.5 mm inside diameter under the same conditions out as described in Example 3, with a chelate resin "of the iminodiacetic acid type (" Dovrex A-1 "from Dow Chemical Co., Ltd. or "Duolite CC-3" from Diamond Shamrock Co., Ltd. or "Diaion CR-10" by Mitsubishi Kasei Co., Ltd.) is packaged. The mercury content of each filtrate after passing through the Column is below 0.003 ppm

Example 6

To 10,000 parts of a sulfuric acid solution of anthraquinone-1,8-disulfonic acid, which contains 74-6 parts of anthraquinone-1,8-disulfonic acid and 1280 ppm of mercury, 20,000 parts of water and 150 parts of sodium thiosulfate (NaoSoO ^^ HoO) are added, and the mixture is then heated and reacted under reflux for 3 hours. The solution is then ^{cooled to 30 °} C. in order to precipitate mercury sulfide, which is then filtered off. The filtrate is then sown by adding 1350 parts of potassium sulfate to precipitate potassium anthraquinone-1,8-disulfonate, which is filtered off and washed with a 3% potassium sulfate solution. 4-5000 parts of the filtrate obtained in this way have a mercury content of 3 ppm and a sulfuric acid concentration of 18%, while the anthraquinone disulfonic acid concentration is 3 % .

The mercury content of the dried potassium anthraquinone 1,8-disulfonate, that is obtained in this way is less than 1/1000 of the content that is achieved if the thio sulfate treatment is omitted.

Then, the 45000 parts of the filtrate is 900 parts is added 35% hydrochloric acid and 330 parts Natriümchlorat, and the mixture is reacted for 3 hours at 95 ⁰ C to 100 ⁰ C.

The solution is ^{cooled to 30 °} C. in order to precipitate precipitates, which are then filtered off. The S ¹ U tr at is followed by a

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Column with an inner diameter of 18.5 mm packed with j? 0 ml "MEP-100" is packed so that 200 bed volumes of the filtrate "at a flow rate of 2 bed volumes per Hour. The mercury content of the by the filtrate passed through the column is below 0.002 ppm.

Example 7

To a according to example 6 after Natriumchloratbehandlung filtrate obtained 55 parts of sodium thiosulfate (Ha ^ S ^ O '5HoO) are after heating to 100 ⁰ C added and then the mixture was stirred' at the same temperature for 3 hours. Then, the solution 30 is ^{It is} cooled to 0 ° C. in order to precipitate precipitates, which mainly consist of mercury sulphide, which is then filtered off. The mercury content of the final filtrate is 0.002 ppm.

Example 8

A filtrate obtained according to Example 6 after filtering off the precipitate after the sodium chlorate treatment is neutralized to pH 8 with 17,400 parts of 40% strength sodium hydroxide solution. 15 parts of a 20% strength solution of sodium diethyldithiocarbamate are then added, and the mixture is ^{stirred at 30 °} C. for 1 hour. The solution is then filtered through a filter paper that has been previously covered with an activated carbon. The result is a filtrate with a mercury content of 0.003 ppm.

Claims;

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Claims (9)

Pat entan sayings Ty process for the removal and recovery of mercury or mercury-containing compounds from a solution of oc-anthraquinone sulfonic acids or their salts, which contains mercury or mercury-containing compounds, which are used as a sulfonation catalyst, characterized in that (a) first the solution with a thiosulfate under Precipitation of the mercury or the mercury compound contained therein is treated as mercury sulfide and the precipitate is filtered off and (b) in a second stage the a-anthraquinonesulfonic acids or their salts are separated off by salting out, the wastewater is treated with a halogenate in the presence of hydrogen halide and the wastewater obtained is with a mercury-adsorbing substance with adsorption of the content of mercury or mercury compound or treated with a thiosulfate with precipitation of the content of mercury or mercury compound as mercury sulfide. 2. The method according to claim 1, characterized in that it is e t that as thiosulfate in the first and second stage Sodium thio sulfate, ammonium thib sulfate, EaI iumthi ο sulfate or Calcium thiosulfate is used. 3. The method according to claim 1, characterized in that that in the first stage an amount of thi ο sulfate is used in 3 to 50 times the amount of the chemical equivalent will. 30984 5/1104 4 · Procedure according to claim. 1, characterized in that that in the second stage an amount of TMosulfate in the 300 to 3000 times the amount of the chemical equivalent is used. 5 × The method according to claim 1, characterized e.icn gekennz - net that the treatment is carried out with the thiosulfate in the first and second stages at a temperature of 80 ⁰ C until Eückflußtemperatur for a period of 3 to 10 -hour. 6. The method according to claim 1, characterized in that that a chlorate, bromate or iodate is used as the halogenate. 7 · Method according to claim 1, characterized in that it is marked. net that an amount of halogenate of 1 to 3 moles per mole α-Anthraquinone sulfonic acid or salt thereof, which is found in wastewater unfold is used. 8. The method according to claim 1, characterized in that the treatment with the halogenate is carried out in the presence of hydrogen halide at a temperature of 50 ⁰ G to the reflux temperature for a period of 2 to 6 hours. 9. The method according to claim 1, characterized gekennzeich.-n.e t that cnelate resins are used as the silica adsorbing substance of the dithizone type, chelating resins of the iminodiacetic acid type, sulfur-containing urea-formaldehyde resins, thiol compounds or dialkyldithiocarbamic acid compounds can be used. 3 0 9845/1 1ΠΛ